The singer admits she has suffered depression and once had to be physically saved by her dad, Achy Breaky Heart star Billy Ray, who burst through a locked door to rescue her.

“I went through a time where I was really depressed,” she reveals. “Like, I locked myself in my room and my dad had to break my door down.”

Miley, 21, says the illness was triggered by the insecurity she felt when she suffered from acne.

She continues: “It was a lot to do with... I had really bad skin and I felt really bullied because of that. But I never was depressed because of the way someone else made me feel. I just was depressed.”

But, she says, it’s the thought of preventing her fans from suffering the same way she did that motivates her to continue performing – as she says many tell her she inspires them.

“They know that I’ve struggled with depression and that helped them get over theirs,” she says. “That gives me a big purpose – a reason to wake up in the morning that’s bigger than to put on my feathers and my little outfits.”

No one should really need a reason to put on feathers... but this bodes well for next month’s UK leg of her Bangerz tour.

Elsewhere in a new chat with Elle magazine, Miley says she found breaking away from Disney more difficult than breaking up with her fiancé, Hunger Games star Liam Hemsworth.

He’ll be pleased.

The singer, who started her career as a squeaky-clean teen on Disney Channel’s Hannah Montana, says: “When I went through a really intense break-up – you know, I was engaged – the thing that gave me the most anxiety was not knowing what to do with myself when Disney wasn’t there to carry me any more or if I didn’t have him.

“And now I’m free of both of those things and I’m fine.

“I lay in bed at night by myself and I’m totally OK and that’s so much stronger than the person three years ago, who would have thought they would have died if they didn’t have a boyfriend.”